well i guess the first question is what system do you have? or will you just be emulating the game? i personally think blue rescue team is a great starting place to just introduce you to the mechanics and such, but you can't go wrong with explorers of time/darkness/sky either, those being the most high acclaimed i've noticed. i'm probably not the best to answer this tho bc i haven't played anything past the explorers title, but they still seem to be called the best in the series tho so i guess that answers it somewhat aha. but pmd isn't something where you necessarily have to play all the games in the spin off to understand it. i don't believe the stories really connect in that way. so you're good to start anywhere, tbh.